1. Field of the Invention
The present invention relates to a modular element for the absorption of oily substances from the surface of water bodies.
2. Description of the Related Art
The need is well-known for having available effective means for coping with the accidental pollution of the surface of the sea caused by, for example, failures or accidents undergone by tankers, pipelines and the like. Although, clearly, the best safeguard of marine or lake ecosystems is prevention of accidental leakages of petroleum or hydrocarbons, as long as the present transport systems, via sea, of petroleum and its derivatives are used, the problem of efficaciously facing possible localized pollution will continue to arise.
Present systems for removing petroleum and other polluting agents from the surfaces of water bodies use floating barriers which perform the function of bounding the polluted spot, so as to prevent it from spreading by wind and streams, while simultaneously allowing intervention by vessels capable of sucking the polluted liquid layer from the water surface and separating the hydrocarbons from the water. Such systems display the drawback that they are only effective under weather conditions which are not too unfavorable, because with choppy seas and with strong winds, the floating barriers no longer offer continuity of protection and can easily capsize. A further disadvantage effecting such systems is that the sucking systems which suck the surface liquid layer are only effective when the thickness of the polluting agent is considerable (higher than 1-2 cm); otherwise, i.e., when the polluting agent has already expanded along sea surface, the separation system must handle too large water volumes relative to the polluting agent to be separated.
In order to obviate such drawbacks, polluting agent-removal systems were proposed which use absorbent elements comprising an external porous sheath suitable for enclosing a fibrous absorbent material.
Such systems are known, e.g., from European Patent Application EP No. 295 911, which discloses a mattress or an elongated element comprising a porous external layer of non-woven polyolefinic fibres containing porous particles, with the external layer being sewn with an elastic yarn in such a way as to define equidistant seam lines.
European Patent Application EP No. 69 675 illustrates an absorbent carpet for hydrocarbons in which a plurality of absorbent granules based on cellulose fibres are interposed between container nets made from yarns constituted by polyester filaments, with mesh size smaller than the granule size.
Such systems known from the prior art are affected by the drawback that they must use large volumes of absorbent elements because, in the initial condition, i.e., before the absorption, a large fraction of the total volume is occupied by the "pores" of the absorbent particles. Clearly, such a large volume, relative to the amount of absorbable agent per unit weight of absorbent element, determines limitations in the amount of absorbent elements which can be transported to the intervention site, which may often be far away from coast. Furthermore, the porous particles used to date suffer from limited recyclability, because wringing out a high percentage content of the polluting agent absorbed inside them is difficult. In some cases, destroying the absorbent elements by incinerating them is preferred.